Dual aligner assembly

ABSTRACT

A dual aligner assembly including a plurality of aligners, including a first aligner and a second aligner. The first aligner has a first shape corresponding to a set of target tooth positions and applies an orthodontic force against a set of target teeth. The first orthodontic force generates movement of the set of target teeth to the set of target tooth positions. The second aligner has a second shape corresponding to a combination of current tooth positions of the set of target teeth, the set of target tooth positions, and a thickness of the first aligner. The second aligner partially encloses the first aligner and provides an anchor for at least a portion of the first aligner. Via the anchor, a combination of the first aligner and the second aligner provides an orthodontic force that prevents the set of target teeth from moving to unwanted tooth positions during orthodontic treatment.

RELATED APPLICATIONS

This application claims priority to and benefit of U.S. PatentApplication No. 62/189,384 filed on Jul. 7, 2015 entitled “DUAL ALIGNERASSEMBLY” by Wu et al., and assigned to the assignee of the presentapplication.

The subject matter of the following patent applications is related tothe present application: U.S. application Ser. No. 15/202,342, filedJul. 5, 2016, entitled “MULTI-MATERIAL ALIGNERS”, which claims thebenefit of U.S. Provisional Application No. 62/189,259, filed Jul. 7,2015, and U.S. Provisional Application No. 62/189,282, filed Jul. 7,2015.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

FIELD OF THE INVENTION

This invention relates in general to a system of repositioning teeth foruse in orthodontic treatment. More particularly, this invention relatesto the use of orthodontic appliances for producing tooth movements.

BACKGROUND

Orthodontic treatments involve repositioning misaligned teeth andimproving bite configurations for improved cosmetic appearance anddental function. Repositioning teeth is accomplished by applyingcontrolled forces to the teeth over an extended period of time. This isconventionally accomplished by wearing what are commonly referred to as“braces”. Braces comprise a variety of appliances such as brackets,bands, archwires, ligatures, and O-rings. After they are bonded to theteeth, periodic meetings with the orthodontist are required to adjustthe braces. This involves installing different archwires havingdifferent force-inducing properties or by replacing or tighteningexisting ligatures. Between meetings, the patient may be required towear supplementary appliances, such as elastic bands or headgear, tosupply additional or extraoral forces.

Although conventional braces are effective, they are often a tedious andtime consuming process requiring many visits to the orthodontist'soffice. Moreover, from a patient's perspective, they are unsightly anduncomfortable. Consequently, alternative orthodontic treatments havebeen developed. A particularly promising approach relies on the use ofelastic positioning appliances for realigning teeth. Such appliancescomprise a thin shell of elastic material that generally conforms to apatient's teeth but is slightly out of alignment with the initial toothconfiguration. Placement of the elastic positioner over the teethapplies controlled forces in specific locations to gradually move theteeth into the new configuration. Repetition of this process withsuccessive appliances comprising new configurations eventually moves theteeth through a series of intermediate configurations to a final desiredconfiguration. A full description of an exemplary elastic polymericpositioning appliance is described in U.S. Pat. No. 5,975,873, assignedto the assignee of the present invention, and incorporated by referencefor all purposes.

In addition to their ease of use, polymeric positioning appliances aregenerally transparent, providing an improved cosmetic appearance, andimpart substantial force on the teeth, due to stiffness of theappliance. Each aligner shell has an inner shape that is configured tomove the patient's teeth to the next planned position. However, when apatient's teeth do not follow this planned movement by not moving ormoving in an unplanned direction, a “lag of movement” occurs. When thislag of movement becomes too great, that is, when the difference betweenthe current position of the patient's teeth and the planned position atwhich the aligner is to move the teeth becomes too great, in many cases,the aligner is no longer able to be snapped onto the patient's teeth.Accordingly, improved appliances and techniques are needed to reducethis lag in movement during orthodontic treatment, and to reduceunwanted tooth movements.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present invention are illustrated by way of example, andnot by way of limitation, in the accompanying drawings, wherein:

FIG. 1A illustrates the dual aligner assembly, in accordance with anembodiment.

FIG. 1B illustrates an enlarged section A of the dual aligner assemblyshown in FIG. 1A, in accordance with an embodiment.

FIG. 2A illustrates the dual aligner assembly, in accordance with anembodiment.

FIG. 2B illustrates a dimple formed in the inner aligner as an exteriorprotrusion, in accordance with an embodiment.

FIG. 2C illustrates a gap formed between the inner aligner and the outeraligner of the dual aligner assembly, in accordance with an embodiment.

FIG. 2D illustrates a ridge formed within a gap, as an exteriorprotrusion of the dual aligner assembly, in accordance with anembodiment.

FIG. 2E illustrates a ridge formed within a gap, as an exteriorprotrusion, in accordance with an embodiment.

FIG. 2F illustrates a ridge formed by a continuous protrusion in analigner surface, in accordance with an embodiment.

FIG. 2G illustrates a continuous ridge disposed in an appliance cavityin a vertical orientation, in accordance with an embodiment

FIG. 2H illustrates a non-continuous ridge disposed in an alignersurface and vertically oriented, in accordance with an embodiment.

FIG. 2I illustrates a cross sectional view of the ridge.

FIG. 3A illustrates aligner action using a conventional aligner.

FIG. 3B illustrates aligner action using a conventional aligner.

FIG. 3C illustrates a dual aligner assembly snapped onto the patient'steeth, in accordance with an embodiment.

FIG. 3D illustrates a dual aligner assembly snapped onto the patient'steeth, in accordance with an embodiment.

FIG. 4A illustrates a conventional aligner system.

FIG. 4B illustrates a side-perspective view of the conventional alignersystem of FIG. 4A.

FIG. 4C illustrates a dual aligner assembly snapped onto the patient'steeth, in accordance with an embodiment.

FIG. 5A illustrates a single aligner of a conventional aligner systempressing against the lingual surface of the teeth.

FIG. 5B illustrates a dual aligner assembly, in accordance with anembodiment.

FIG. 6 illustrates an example jaw, which is variously depicted in FIGS.1A, 5A and 5B, together with an dual aligner assembly which has beenconfigured in accordance with an embodiment.

The drawings referred to in this description should be understood as notbeing drawn to scale except if specifically noted.

SUMMARY OF EMBODIMENTS

In one embodiment, a dual aligner assembly includes a plurality ofaligners. The plurality of aligners includes a first aligner and asecond aligner. The first aligner includes a first material having afirst shape corresponding to a set of target tooth positions, whereinthe first aligner applies a first orthodontic force against a set oftarget teeth of a plurality of teeth of a dental arch of a patient,wherein the first orthodontic force generates movement of the set oftarget teeth to the set of target tooth positions. The second alignerincludes a second material having a second shape corresponding to acombination of current tooth positions of the set of target teeth, theset of target tooth positions, and a thickness of the first aligner,wherein the second aligner partially encloses the first aligner andprovides an anchor for at least a portion of the first aligner, whereinvia the anchor, a combination of the first aligner and the secondaligner provides added support for the accurate movement of the targetteeth to the set of target tooth positions via the first orthodonticforce and prevents the set of target teeth from moving to unwanted toothpositions during orthodontic treatment.

In one embodiment, the first aligner is an inner aligner that ispartially enclosed by an outer aligner. In another embodiment, thesecond aligner is an outer aligner that partially encloses an inneraligner. In yet another embodiment, the second aligner is an inneraligner that is partially enclosed by a third aligner.

In one embodiment, the unwanted tooth positions include tooth positionsother than the following tooth positions: the current tooth positions ofthe set of target teeth; one or more tooth positions that representmovement of at least one tooth of the set of target teeth to the set oftarget tooth positions; and the set of target tooth positions.

In one embodiment, the second aligner is more rigid than the firstaligner. In one embodiment, the second aligner is less rigid than thefirst aligner. In one embodiment, the second aligner is equal inrigidity to the first aligner.

In one embodiment, the first aligner includes: a first force enlargementelement. The first force enlargement element includes: a contact regionbetween the first aligner and the second aligner, wherein the contactregion provides an anchor point at the second aligner and for the firstaligner, whereby the first orthodontic force, via the anchor point andby the first aligner, is increased against at least one tooth of the setof target teeth.

In one embodiment, the first force enlargement element includes adimple. In another embodiment, the first force enlargement elementincludes a ridge. In yet another embodiment, the first force enlargementelement includes an outward protrusion. A dimple and a ridge, in someinstances, are formed to be outward protrusions.

In one embodiment, the dual aligner assembly includes a second forceenlargement element. The second force enlargement element includes: anon-contact region between the first aligner and the second aligner,wherein the non-contact region provides an area into which a movement ofat least one tooth of the set of target teeth to at least one targettooth position of the set of target tooth positions is accomplished. Inone embodiment that includes the second force enlargement element, thefirst aligner includes a dimple. In another embodiment that includes thesecond force enlargement element, the first aligner includes a ridge. Inyet another embodiment that includes the second force enlargementelement, the first aligner includes an outward protrusion.

In one embodiment, the plurality of aligners further includes: a thirdaligner that includes a second material having a third shapecorresponding to a combination of the current tooth positions of the setof target teeth, the set of target tooth positions and a thickness ofthe second aligner, wherein the third aligner partially encloses thesecond aligner and provides an anchor for at least a portion of thesecond aligner, wherein via the anchor, a combination of the firstaligner, the second aligner and the third aligner provides a thirdorthodontic force that prevents the set of target teeth from moving tounwanted tooth positions during orthodontic treatment. In oneembodiment, including the third aligner, the unwanted tooth positionsinclude tooth positions other than the following tooth positions: thecurrent tooth positions of the set of target teeth; one or more toothpositions that represent movement of at least one tooth of the set oftarget teeth to the set of target tooth positions; and the set of targettooth positions.

In one embodiment, the third aligner is an inner aligner that ispartially enclosed by an outer aligner. In another embodiment, the thirdaligner is an outer aligner that partially encloses an inner aligner. Inyet another embodiment, the third aligner is an inner aligner that ispartially enclosed by a fourth aligner. Of note, the fourth aligner, inone embodiment, includes the features described herein in relation tothe third aligner, except that the fourth aligner also accommodates notonly the features of the first and second aligner, but also accommodatesthe features of the third aligner.

In one embodiment, a dual aligner assembly includes: a plurality ofaligners. The plurality of aligners includes a first aligner and asecond aligner. The first aligner includes a first material having afirst shape corresponding to a first set of target tooth positions,wherein the first aligner applies a first orthodontic force against aset of target teeth of a plurality of teeth of a dental arch of apatient, wherein the first orthodontic force generates movement of theset of target teeth to the first set of target tooth positions. Thesecond aligner includes a second material having a second shapecorresponding to a combination of current tooth positions of the set oftarget teeth, the first set of target tooth positions, at least a secondset of target tooth positions, and a thickness of at least the firstaligner. The second aligner partially encloses the at least firstaligner and provides an anchor for at least a portion of the at leastfirst aligner. Via the anchor, a combination of the first aligner andthe second aligner and any intermediate aligner positioned between thefirst aligner and the second aligner provides added support for themovement of the target teeth to the set of target tooth positions andprovides a second orthodontic force that prevents the set of targetteeth from moving to unwanted tooth positions during orthodontictreatment.

DESCRIPTION OF EMBODIMENTS

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various embodiments of thepresent invention and is not intended to represent the only embodimentsin which the present invention may be practiced. Each embodimentdescribed in this disclosure is provided merely as an example orillustration of the present invention, and should not necessarily beconstrued as preferred or advantageous over other embodiments. In someinstances, well known methods, procedures, objects, and circuits havenot been described in detail as not to unnecessarily obscure aspects ofthe present disclosure.

Overview of Discussion

Embodiments disclosed herein include a dual aligner assembly for movingteeth to a desired position. For example, the dual aligner assemblyincludes an outer aligner, and at least one inner aligner. The inneraligner(s) is formed based on the patient's teeth position in the nextstage. In one embodiment, the inner aligner(s) is made of soft and thinpolymeric film. The outer aligner is formed based on the combination ofthe current position and the “next” position of the patient's teeth, aswell as the thickness of the inner aligner(s). In one embodiment, theouter aligner is made of hard and thick polymeric film. (It should benoted that in various embodiments, the inner and outer aligner may becomposed of material having more, less, or the same amount of rigidity.)The outer aligner functions as anchorage for the inner aligner(s),enabling the inner aligner(s) to move the patient's teeth to desiredpositions with larger and more accurate forces than enabled byconventional aligner systems.

The dual aligner assembly, in various embodiments, includes protrusions(e.g., dimples, ridges) that increase the engagement between the outeraligner and the inner aligner(s), thereby providing even greateranchorage support to the inner aligner(s). For example, dimples and/orridges may be formed in the inner aligner and fill a portion of the gapbetween the outer aligner and the inner aligner(s) or between multipleinner aligners. These dimples and/or ridges aid in creating moreaccurate forces near the patient's gingival line to move the patient'steeth to the desired teeth positions.

Thus, embodiments enable an increase of force that may be applied by theinner surface of the most inner aligner against a patient's tooth orteeth in order to move the patient's teeth to desired tooth positions.Using this novel technology, difficult tooth movement may beaccomplished, such as posterior arch expansion, pure translation andmultiple teeth extrusion. For example, a multiple anterior toothextrusion may be performed to fix a patient's open bit, a posteriordistalization may be performed to create space in order to resolvespacing issues in a patient's bit, and a patient's posterior cross biteor scissor bite may be fixed by moving a patient's molar faster thanwould be accomplished with conventional technology. Of note, theembodiments described herein may be applied to achieve any type of toothmovement, in any direction, in any arbitrary plane of space.

The discussion begins with a description of a conventional alignersystem. Continuing, the discussion turns to a description of embodimentsof a novel dual aligner assembly, according to various embodiments.

FIGS. 1A and 1B illustrate the dual aligner assembly, in accordance withembodiments.

FIGS. 2A-2E illustrate sections of various dual aligner assemblieshaving been snapped onto the patient's teeth, including example dimpleand ridge protrusions, in accordance with embodiments. FIGS. 2F-2Iillustrate example designs/configurations of ridged protrusions.

FIGS. 3A and 3B illustrate aligner action resulting from implementationof a conventional aligner. FIGS. 3C and 3D illustrate aligner actionresulting from implementation of the dual aligner assembly. FIGS. 4A and4B illustrate aligner action resulting from implementation of aconventional aligner. FIG. 4C illustrates aligner action resulting fromimplementation of the dual aligner assembly.

FIG. 5A illustrates the limitations of a conventional aligner system andthe benefits of the novel dual aligner assembly. FIG. 5B illustrates thenovel dual aligner assembly in operation.

Conventional Aligner System

Conventional aligner systems are used to treat thousands of mild andmoderately difficult orthodontic cases each month. Conventional alignersystems include many technological improvements that improve thepredictability and performance of the product, thereby also enabling theconventional aligner system to treat more difficult orthodontic cases.

For example, such technological improvements include optimizedattachments, power ridges, and rubber bands. Some optimized attachmentsare shown to improve the rotation of premolars and canines to fix severecrowding, while other optimized (extrusion) attachments are shown toextrude anterior incisors to fix an open bite. The power ridgetechnology is shown to move the root lingually, to improve the clinicalprofile of an upper jaw. The rubber band technology is shown to help A/Pmovement (NP class correction). Even given the latest technologicalimprovements, there currently exist many limitations to aligner systems.

In the conventional aligner system, the tooth's initial position isacquired from the patient's initial impression without treatment. Thetreatment goal is set up by the software and/or the user as the finaldesired position. Between the tooth's initial position and the tooth'sfinal position, some intermediate positions are created through toothpath planning and can be assigned the symbols i (tooth's initialposition) and i+1 (an intermediate position). To achieve the movementfrom i to i+1, the patient wears the aligner that is manufactured basedon the position i+1.

One major problem with the conventional aligner system is the lack ofpredictability of tooth movement, such as when teeth do not follow theplanned tooth movement from i to i+1 and when the lag of the movementfrom i to i+1 is too large. When the lag is too large, the differencebetween the current teeth position and the aligner is also too large sothat the aligner cannot be snapped onto the teeth anymore. When thissituation occurs, the planned treatment has to be restarted (“middlecourse correction”), the remaining manufactured aligners are wasted, andthe required treatment time is extended.

One of the causes of the movement lag is that the force from the aligneris too small or not in the correct direction of the desired toothmovement. The aligner itself is plastic and is in the shape of teeth,and the force created by the aligner placed on the teeth comes from thedeformation of the plastic shell of the aligner. The deformation iscaused by the patient's teeth pushing against the plastic shell. Ingeneral, the conventional aligner is more rigid near the incisal edge ofthe patient's tooth and is weaker near the gingival line of thepatient's tooth. Thus, the same deformation created by the patient'steeth pushing against the plastic shell at the gingival line willproduce less force than the patient's teeth pushing against the plasticshell at the incisal edge. Additionally, when the plastic shell isdeformed near one tooth at the gingival line, the plastic shell opens upand it is possible that the plastic shell does not touch nearby teethnear the gingival line.

Yet another problem with conventional aligners involves the groupmovement of teeth, such as when all the teeth are moved in the samedirection. For example, when performing an arch expansion procedure, thepatient's posterior teeth are moved as a group in the buccal direction.In this situation, there is only deformation between the posterior teethand other teeth. No force is created inside the group of posteriorteeth. Thus, only the boundary teeth of this group of posterior teethcan be moved, while other teeth may still remain in the initial toothposition. This problem can be solved by moving each tooth of the groupof posterior teeth one by one. However, moving teeth one by one requiresmore treatment time and requires more aligners to be manufactured,thereby increasing the treatment costs.

Dual Aligner Assembly

The novel dual aligner assembly, according to embodiments and as will bedescribed herein, resolve at least the foregoing issues. In oneembodiment, the dual aligner assembly includes the following structuralfeatures:

1) An inner aligner that is softer and thinner than the outer aligner.The inner aligner is manufactured based on the teeth position of thenext stage (e.g., i+1). The inner aligner is used to create small andconstant orthodontic force to move the teeth. Of note, while the term,“inner aligner” is used most often herein to discuss the structuralfeatures of the dual aligner assembly, the term “first aligner” is alsoused to describe the inner aligner, according to one embodiment.

(In another embodiment however, the term inner aligner is used to referto an aligner that is manufactured based on the teeth position of anyposition of a stage of treatment that comes after the teeth position ofthe next stage, such as i+1+n where n is any stage of treatment afterthe treatment stage that follows the current position of the teeth.)

2) The outer aligner is stronger and thicker than the inner aligner. Theouter aligner is big enough to hold the inner aligner. The inner aligneris able to anchor onto the outer aligner and use the outer aligner assupport to provide larger and more accurate forces against the patient'steeth as the patient's teeth deform the inner aligner. Of note, whilethe dual aligner assembly is most often discussed herein in terms of“outer aligner”

3) The outer aligner is large enough to hold the teeth position from theinitial position, i, to the next position, i+1, such that there is notextract force if the patient's teeth movement follow the plannedmovement treatment.

4) Features, such as dimples and/or ridges, may be added to the inneraligner to push the teeth. Dimples and/or ridges may be added to theouter aligner to create larger and more accurate forces to push thepatient's teeth toward the next position, i+1.

Of note, while the dual aligner assembly is described in general withreference to an inner aligner and an outer aligner, it should beunderstood that the dual aligner assembly may include multiple inneraligners, each inner aligner capable of including the features describedbelow. Further, while the dual aligner assembly is described in generalwith reference to an outer aligner being of a more rigid compositionthan the inner aligner, it should be understood that the dual alignerassembly may function as intended with an outer aligner being of a lessrigid composition or of a composition with an equivalent rigiditycompared to the inner aligner(s), in accordance with an embodiment.

The following is a brief description of at least some of the advantagesand the benefits resulting from implementation of various embodiments ofthe dual aligner assembly, as will be described herein.

1) Increased Control of Gingival Force and Root Movement: When the dualaligner assembly is snapped onto the patient's teeth, and the patient'steeth push against the inner surface of the inner aligner, the inneraligner deforms and opens up. Portions of this deformation, on the outersurface of the inner aligner, push against the inner surface of theouter aligner. Since, in some embodiments, the outer aligner is morerigid than the inner aligner, the pushing of the patient's teeth againstthe inner aligner does not easily cause the outer aligner to also deformand open up. Since the outer aligner has a greater rigidity than theinner aligner, in response to the inner aligner pushing against theouter aligner due to the deformation, the outer aligner pushes backagainst the inner aligner with a designated force that causes the inneraligner to press against the patient's teeth to effect a plannedmovement treatment of the patient's teeth to the desired position.

For example, since the outer aligner is stronger and more rigid than theinner aligner near the gingival line, the pressing of the outer aligneragainst the inner aligner causes the force with which the inner surfaceof the inner aligner presses against the patient's teeth to be increasedat the gingival line. Whereas, without the dual aligner assembly, theconventional aligner would open up at the gingival line and not be ableto create the necessary force to press against the gingival line of thepatient's teeth; the novel dual aligner assembly described hereinprovides a force for applying pressure against the patient's teeth in aplanned movement treatment.

2) Increased Control of Group Movement and Posterior Expansion: Invarious embodiments of the dual aligner assembly, the inner alignerincludes at least one dimple and/or ridge (as will be explained belowwith reference to FIGS. 2A-2E) designed to deform and create force topush against a particular tooth that is to be moved according to aplanned movement treatment. As will be explained below in detail herein,since the outer aligner is more rigid than the inner aligner, once thedual aligner assembly is snapped onto the patient's teeth, each ridgeand/or dimple of the inner aligner may be deformed outward (in thedirection toward the outer aligner) by the patient's teeth pressingagainst the inner surface of the inner aligner. The outer surface of thedimple and/or ridge of the inner aligner then contacts the more rigidinner surface of the outer aligner. The outer aligner resists themovement outward of the edges of the dimples and/or ridges where thedimples and/or ridges contact the outer aligner (contact points),thereby causing the inner surface of the inner aligner to press against(push back with an equal and opposite force as that force applied by theinner aligner against the outer aligner) the patient's teeth atpositions corresponding to the positions of the dimples and/or ridges.

3) Increased Control of Rotation of Premolar and Canine Teeth: Invarious embodiment of the dual aligner assembly, the more rigid outeraligner holds the inner aligner close to the patient's teeth, such thatthe inner aligner pushes the patient's teeth in a tangent direction,thereby creating rotation torque (as will be explained below withreference to FIGS. 3A-3D).

4) Increased Guidance and Predictability of Tooth Movement: In variousembodiments of the dual aligner assembly, while the inner alignergenerates force (via engagement with the outer aligner at predeterminedpositions) to achieve the planned tooth movement, the outer alignerprovides tooth movement guidance. This will provide extra guidance formovement of the patient's teeth, compared to conventional aligners,thereby making the patient's tooth movement more predictable.

5) Increased Compliance with a Tooth's Biological Response: According tovarious embodiments wherein the inner aligner is softer and thinner thanthe outer aligner and the outer aligner is larger than the inneraligner, the dual aligner design creates more flexibility with regard todesign, thereby enabling the patient's biological response to thetreatment to comply with the patient's natural tooth movement.

FIG. 1A illustrates the dual aligner assembly 100 together with apatient's dental arch 118, in accordance with an embodiment. FIG. 1Ashows the dual aligner assembly 100 snapped onto the dental arch 118 ofa patient. The dual aligner assembly 100 includes multiple aligners,wherein at least one inner aligner 106 is housed within an outer aligner104. For example, in one embodiment, and as shown in FIG. 1A, the dualaligner assembly 100 includes the inner aligner 106 and the outeraligner 104.

The inner aligner 106 is the aligner that is positioned to be closer tothe patient's teeth 102. The inner aligner 106 is designed andmanufactured to hold the patient's teeth 102 in the desired nextposition (e.g., i+1). In one embodiment, the inner aligner 106 is madeof a soft and thin plastic film and delivers small and constantorthodontic force to the patient's teeth 102 at predetermined contactpoints, such as at contact region one 108 and contact region two 116.The shape of the inner aligner 106 is the shape of all of the patient'steeth 102 posited in the next position of treatment, i+1, such as thetarget tooth position 114. FIG. 1A shows the patient's tooth 120 in itscurrent position. As can be seen, the inner aligner 106 is shaped toaccommodate holding the patient's tooth 120 in the target tooth position114.

The outer aligner 104 partially encloses the inner aligner 106 and isdesigned to hold the inner aligner 106 and to hold the patient's tooth120 in either the tooth's current position 110 or the target toothposition 114, or any tooth position representing planned treatmentmovement to achieve the target tooth position 114 from the tooth'scurrent position 110. The outer aligner 104 is made of hard or thickplastic film and provides anchorage for the inner aligner 106. The shapeof the outer aligner 104 is the shape of the combined shapes of thepatient's teeth 102 in their current position 110 and patient's teeth102 in the target tooth position 114. The shape of the outer aligner 104also accommodates the thickness of the inner aligner 106.

Thus, if the patient's tooth 102 is moving to the target teeth position114, i+1, then the outer aligner 104 does not create any extract forcesagainst the patient's tooth 120 (or teeth). However, if the patient'stooth 102 is even slightly wavering (moving away) from the determinedmovement pathway from the tooth's current position 110, i, to the targetteeth position 114, i+1, then the outer aligner 104 presses against theinner aligner 106, thereby creating an extracting force against thepatient's tooth 120 that is wavering from the desired treatment movementpathway. Of note, the description herein regarding the dual alignerassembly 100 is described in terms of the patient's tooth 120 for thepurposes of brevity and clarity in explanation, but it should beunderstood that the same principals described herein may be applied tomore than one tooth of the patient's plurality of teeth 102.

FIG. 1A also shows the contact region one 108 and the contact region two116. Each contact region includes the section of the inner aligner 106which is contacted by the patient's tooth 120 as well as the material ofthe inner aligner 106 surrounding the contact point (that is affected bythe tooth contact). As seen at contact region one 108 and the contactregion two 116 and illustrating the dual aligner assembly 100 inoperation, the patient's tooth 120 contacts the inner aligner 106. As aresult of this contact, the inner aligner 106 deforms at the contactregions, and the material at the contact regions one 108 and two 116 arestretched outward toward the outer aligner 104. If this stretchedportion contacts the outer aligner 104, the outer aligner 104 functionsto reduce and/or eliminate any further stretching of the inner aligner106 outwards. This reduction and/or elimination of any furtherstretching is effected since the outer aligner 104, in accordance withan embodiment, is designed with a higher rigidity than the inner aligner106. The outer aligner 104 pushes back against the inner aligner 106with the same force at which the inner aligner 106 is pressing againstthe outer aligner 104. The inner aligner 106 then translates this forceto the patient's tooth 120 by pressing against the patient's tooth 120,supported by the anchoring engagement with the outer aligner 104, andguides the patient's tooth 120 toward the target tooth position 114.

FIG. 1B illustrates an enlargement of section A of FIG. 1A. FIG. 1Bshows the contact region two 116 in which the patient's tooth 120 iscontacting the inner aligner 106. Depending upon the particular shape ofthe inner aligner 106, the patient's tooth 120 pushes the inner aligner106 outward a certain distance into the gap area 128. The inner aligner106 and the outer aligner 104 are manufactured such that upon beingpushed some predetermined distance outward, the inner aligner 106contacts the outer aligner 104. While the patient's tooth 120 is able topush the inner aligner 106 outward toward the outer aligner 104 and evencause the inner aligner 106 to contact the outer aligner 104, since theouter aligner 104 is stronger and more rigid than the inner aligner 106,the patient's tooth 120 is less able to also cause the outer aligner 104to be pushed outwards. In response to inner aligner 106 pressing againstthe inner surface of the outer aligner 104, the outer aligner 104 pushesback against the inner aligner 106, and hence the patient's tooth 120,with an equal and opposite force. Thus, the inner aligner 106 anchorsagainst the outer aligner 104 and translates the force pressed againstits outer surface, from the outer aligner 104, to the patient's tooth120.

Next, the potential contact region 126 near the patient's second tooth124 will be discussed. If the dual aligner assembly 100 is designed suchthat the patient's second tooth 124 moves and contacts the inner aligner106 within the potential contact region 126, the outer aligner 104 willprevent the inner aligner 106 from stretching outward much further (ifany further), thereby substantially stopping the outward stretching ofthe inner aligner, and therefore keep the patient's second tooth 124within a certain predetermined distance from its original position.Thus, even though the movement of one tooth or the pressure applied bythe aligner on one tooth may cause movement in another neighboringtooth, the outer aligner may be designed to reduce or eliminate thisunwanted movement of the patient's neighboring tooth.

Shaped Features for the Inner Aligner (e.g., Dimple, Ridge)

In various embodiments, the inner aligner is manufactured to includeshaped features thereon, such as, but not limited to, dimples and/orridges. Since the outer aligner is larger than the inner aligner, inmany situations, there may be some gap area between the two aligners.This gap area can be filled by these shaped features, thereby enablinginteractivity between the inner aligner and the outer aligner. As willbe explained, with reference to FIGS. 2A-2E, shaped features, such as adimple and/or a ridge, will provide extract and controllable forces topush the patient's teeth toward target tooth positions. Of note, whileFIGS. 2A-2E illustrate dimples and ridges, it should be understood thatthe shaped features may be of a shape other than dimples and ridges, butthat are capable of providing extract and controllable forces as will bedescribed herein.

Various designs, orientations, and/or configurations of shaped featuresare available for use according to embodiments. Shaped features achieveforce profiles favorable to specific types of tooth movement and caninclude both attachment-type features as well as non-attachment typefeatures. Non-attachment type features can include various shapedalterations or protrusions in a surface of the dual aligner assembly,such as ridges (e.g., interior or exterior), dimples, and the like. Theterms “non-attachment type feature” and “protrusion” (e.g., applianceprotrusion) are typically used interchangeably herein. Dimples, forexample, may be protrusions having substantially the same dimensionsalong a width compared to the protrusion length. Ridges, by comparison,for example, are protrusions having an unequal length and width.Interior protrusions, such as interior ridges, include a groove orprotrusion in an inner aligner that recesses toward an inner surface(e.g., tooth contacting surface) of the inner aligner. Exteriorprotrusions and ridges bulge toward an exterior surface of the inneraligner system. Protrusion type features, such as dimples and ridges,can be either filled with material (e.g., composite material) or leftunfilled. If it is filled, the composite can be controlled to solidifyafter the desired shape and/or volume of the filler is obtained. In thefollowing discussion, the general term “feature” will be used. But themethods apply on any feature as appropriate.

In some instances, ridge-shaped protrusions may provide differencesand/or advantages for an application of force to the patient's teethcompared to other protrusion shapes, such as dimples. For example,dimples having a substantially equal length compared to width willtypically provide more of a point application of a force to a surface ofa tooth. By comparison, a ridge-shaped protrusion may allow anapplication of force to be more evenly distributed along a surface of atooth, and may provide more precisely controlled tooth movement in someinstances. Further, ridge-shaped protrusions provide more protrusionconfiguration and design options, provide a greater range of forcevalues that can be selected and delivered to the target tooth comparedto non-ridge shapes (such as dimples), and can therefore be more likelyto impart the desired load against the target tooth. As such, the use ofridges compared to other more simplified shapes (e.g., a single dimple)provide a greater range of available force values or selections forimparting the desired load vector, or force direction and/or magnitudealong a tooth surface, thereby providing more treatment options.

As noted, various designs, orientations, and/or configurations of shapedfeatures are available for use according to the present invention andcan depend, at least partially, on the desired application of force andtooth movement. Exemplary designs/configurations of ridged protrusionsare illustrated with reference to FIGS. 2F-2I, as will be explainedbelow.

FIGS. 2A-2E illustrates sections of various dual aligner assembliestogether with the patient's dental arch, in accordance with embodiments.FIG. 2A illustrates the dual aligner assembly 212, the inner aligner 202and the outer aligner 204 designed in combination, to cause thepatient's tooth to move to the right. The inner aligner 202 ismanufactured based on the next position, i+1 (tooth in target position206), while the outer aligner 204 is manufactured based on thecombination of the tooth in its current position 208, i, and the toothin its target position 206, i+1. In FIGS. 2A-2E, there exists a gap 210between portions of the inner aligner 202 and the outer aligner 204,wherein the gap 210 is a gap near the gingival line.

As shown in FIG. 2A, once the dual aligner assembly 212 is snapped ontothe patient's teeth, the inner aligner 202 (which is designed to holdthe patient's tooth in its target tooth position 206) is pressed outwardtoward the inner surface of the outer aligner 204. The outer aligner 204(which is designed to hold the patient's tooth either in its currentposition 208, in the target position 206, or any position there between)provides extra support to the inner aligner 202. For example, as thepatient's tooth pushes the inner aligner 202 outward, the inner aligner202 contacts the more rigid outer aligner 204 and the outer aligner 204resists the movement outward by the inner aligner 202 via its greaterrigidity. The outer aligner 204 provides anchorage (and thereby support)for the inner aligner 202 to resist the outward movement, therebyenabling the inner aligner 202 to avoid continued expansion outwards.The force with which the inner aligner 202 presses against the outeraligner 204 is received in an equal and opposite direction via the outeraligner 204 pressing back and against the inner aligner 202. Thisreceived force is then translated through the inner aligner 202 to thepatient's tooth. This translated force causes the inner aligner to pressagainst the patient's tooth, guiding the patient's tooth toward thedesired target position 206.

FIG. 2B shows a dimple 222 brined in the inner aligner 214 as anexterior protrusion, near the gingival line and partially filling thegap 220 of the dual aligner 218, according to an embodiment. As shown,the inner aligner 214 is shaped to accommodate the patient's tooth 224in a target position 206. Thus, when the dual aligner assembly 218 issnapped onto the patient's teeth, a portion of the patient's toothpushes against the inner surface of the inner aligner 214, therebystretching the inner aligner 214 outwards toward the outer aligner 216.When stretched outward, the outer edge of the dimple 222 pushes againstthe inner surface of the outer aligner 216. Even though a portion of theinner aligner 214 is stretched outward, the end of the dimple 222 thatpushes against the inner surface of the outer aligner 216 anchorsagainst the outer aligner 216. At this anchorage point, the inneraligner 214, via the support of the outer aligner 216, provides theresistance to the patient's tooth from moving outwards in the directionof the dimple 222. When stretched outward, the outer edge of the dimple222 pushes against the inner surface of the outer aligner 216. Eventhough a portion of the inner aligner 214 is stretched outward, the endof the dimple 222 that pushes against the inner surface of the outeraligner 216 anchors against the outer aligner 216. At this anchoragepoint, the inner aligner 214, via the support of the outer aligner 216,provides the resistance to the patient's tooth from moving outwards inthe direction of the dimple 222.

FIG. 2C shows a gap 236 formed between the inner aligner 226 and theouter aligner 228 of the dual aligner assembly 230, according to anembodiment. As shown, the dual aligner assembly 230 is designed to movethe patient's tooth upward (lingually). There is not a dimple or ridgeformed in the inner aligner 226 and positioned within the gap 236.

FIG. 2D shows a ridge formed within the gap 244, as an exteriorprotrusion if the dual aligner assembly 242, in accordance with anembodiment. As seen, the ridge 246 is filling the gap 244 near thegingival line. The patient's tooth 232 contacts the inner aligner 240.In response to this contact, the inner aligner 240 expands outwardstoward the outer aligner 238. The outside surface of the ridge 246 ofthe inner aligner 240 contacts the inner surface of the outer aligner238. The inner surface of the outer aligner 238 pushes against the outersurface of the ridge 246, The inner surface of the ridge 246 then pushesagainst the patient's tooth to guide it to the target tooth position234.

FIG. 2E shows a ridge 258 formed within a gap 260 of a dual alignerassembly 252 and between the inner aligner 248 and the outer aligner250, as an exterior protrusion, in accordance with an embodiment. Theridge 258 is shown from the perspective of the mesial-distal direction.The ridge 258 enables the engagement of the inner aligner 248 with theouter aligner 250, enabling the inner aligner 248 to use this engagementto help anchor the inner aligner 248 such that the inner aligner 248 mayremain in contact with the tooth. Via this contact, the inner aligner248 applies a force against the tooth, moving the tooth from its currentposition 256 to the target tooth position 254.

FIG. 2F illustrates a ridge 262 formed by a continuous protrusion in analigner surface. While the geometric features of the ridge 262 may varyalong the length, the ridge 262 is continuous in the sense that it isconfigured to contact a tooth surface along an uninterrupted length. Theridge 262 is illustrated as having a more horizontal orientationrelative to the tooth or, in other words, perpendicular to the tooth inthe crown to tooth direction. Referring to FIG. 2G, a continuous ridge264 is illustrated disposed in an appliance cavity in a verticalorientation. FIG. 2H illustrates a non-continuous ridge 270 that isdisposed in an aligner surface and vertically oriented. FIG. 2I shows across-sectional view of the ridge 270, illustrating the sort ofcorrugated surface forming the non-continuous ridge by a series ofdimples or bump-like protrusions 266 a, 266 b, 266 c. As illustrated,such bump-like protrusions can each include a portion of the protrusionthat contacts a tooth surface, with each tooth contacting surface of aprotrusion separated by non-tooth contacting regions of the ridge havinga different height. Parameters of tooth contacting and non-contactingaspects of a non-continuous ridge, as illustrated, can be defined, atleast in part, by fabrication methods (e.g., direct fabrication, vacuummolding, etc.) used. Both continuous and non-continuous type ridgesfunction to apply a force vector along a length of the tooth, ratherthan at a single point with a single dimple or bump-like protrusion.Shaped features, such as midges can be designed in various shapes (e.g.,curve, “L” shaped, “T” shaped, hook, etc.), as well as orientations(e.g., vertical, horizontal, slanted, etc) and are not limited to anyparticular shape or orientation.

Any number of one or more shaped features can be included in design andfabrication of embodiments. In one embodiment, the gap between the inneraligner and the outer aligner can include a plurality of shapedfeatures, such as protrusions. For example, the gap can include at leasttwo shaped features, such as protrusions that are shaped and positionedwithin the cavity, such that each of the protrusions are brought intocontact with the received patient's tooth when the dual aligner assemblyis initially worn by the patient. Thus, a number of protrusions (e.g.,two or more) can be configured and incorporated in the dual alignerassembly such that each of these protrusions will each engage thereceived tooth when the dual aligner assembly is initially worn by thepatient and before the tooth has been moved by the appliance.

Besides protrusions or non-attachment type shaped features, the shapedfeatures of the present invention can optionally include attachment typefeatures. Attachment, as used herein, may be any form of material thatmay be attached to the tooth whether preformed, formed using a templateor in an amorphous form that is attached to the surface of the tooth. Itcan be disposed on the tooth surface using an adhesive material, or theadhesive material itself may be disposed on the surface of the tooth asan attachment.

Generally, the attachments operate to provide “bumps” on a surface ofthe tooth which otherwise would be difficult for the dental appliance togrip. Attachments may also be engaged by the appliance in a manner thatfavors delivery of desired force directions and magnitudes. Attachmentstypically include a material bonded or attached to a surface of thetooth, with a corresponding receiving portion or couple built into thetooth receiving appliance. In one example, an attachment-type featurecan include an orphan attachment, or any appropriate shaped materialbonded to the crown surface, but with no receptacle or receiving portionbuild into the appliance to receive the attachment shape. Instead, thegenerated force concentrates on the contact area between the alignersurface and the attachment.

FIGS. 3A and 3B illustrate aligner action using a conventional aligner.FIGS. 3C and 3D illustrate aligner action using the dual alignerassembly, in which the root of the patient's tooth is movedbuccal-lingually, in accordance with an embodiment. FIGS. 4A and 4Billustrate aligner action using a conventional aligner. FIG. 4Cillustrates aligner action using the dual aligner assembly, in which theroot of the patient's tooth is moved in the mesial-distal direction, inaccordance with an embodiment.

With reference to FIG. 3A, the current position 302 of the patient'stooth 308 is shown, as well as the target tooth position 304 for thepatient's tooth 308. The conventional aligner is shown, having beendesigned to form the shape of the target tooth position 304. As can beseen, the patient's tooth 308 is planned to be moved bucally (to theright direction). The single aligner 306 is formed based on thepatient's target tooth position 304 in the next stage (i+1).

With reference to FIG. 3B, the single aligner 306 is shown snapped ontothe patient's dental arch (in this case, a portion of the single aligner306 is shown snapped onto a patient's tooth 308). Since the patient'stooth 308 is still in its original position, the single aligner 306becomes deformed. Additionally, since the incisal edge 310 is more rigidthan the gingival portion of the single aligner 306, at the incisal edge310, the single aligner 306 remains stiffer and deforms less than otherless rigid portions of the single aligner 306 (in response to contactwith the patient's tooth 308). The portion 312 of the single aligner 306near the gingival line tends to open outward to a certain extent,depending on its degree of rigidity. Thus, since the force with whichpressure is applied against the patient's tooth 308 by the singlealigner 306 is larger near the incisal edge 310 than at the gingivalline, an unwanted torque 314 is created that rotates the patient's tooth308 in an unwanted direction.

With reference to FIG. 3C, a dual aligner assembly 322 is shown snappedonto the patient's teeth, in accordance with an embodiment. FIG. 3Cillustrates a portion of the outer aligner 320 and the inner aligner 318in relation to each other. As can be seen, the inner aligner 318 isformed to be the shape of the target tooth position 328. On the otherhand, the outer aligner 320 is formed to be the shape of the combinationof the current tooth position 330 and the target tooth position 328. Theinner aligner 318 and the outer aligner 320 are formed such that a gap324 is created on one side of the patient's tooth between a portion ofthe area between the inner aligner 318 and the outer aligner 320. On theother side of the patient's tooth, the inner aligner 318 and the outeraligner 320 are formed such that the outer aligner 320 follows the formof the inner aligner 318 closely. Thus, in response to being snappedonto the patient's tooth, the inner aligner 318, which is formed to beshaped in the target tooth position 328, becomes deformed and is pushedoutward by the patient's tooth. However, since the outer aligner is alsoformed to be the shape of the target tooth position 328 on one side ofthe patient's tooth, the outer aligner 320 will prevent the inneraligner 318 at the gingival area from popping outwards and keep theinner aligner 318 in contact with the patient's tooth. Since thepressure applied to the patient's tooth at the gingival line is closerto the root 332 of the tooth, a predetermined (and wanted) amount oftorque 326 is applied, and the root 332 of the patient's tooth may bemoved more efficiently.

With reference to FIG. 3D, a dual aligner assembly 340 is shown snappedonto the patient's teeth, in accordance with an embodiment. FIG. 3Dillustrates a portion of the outer aligner 338 and the inner aligner 336in relation to each other. As can be seen, the inner aligner 336 isformed to be the shape of the target tooth position 344, with a dimple348 formed as an exterior facing protrusion in the inner aligner 336. Onthe other hand, the outer aligner 338 is formed to be the shape of thecombination of the current tooth position 346 and the target toothposition 344. The inner aligner 336 and the outer aligner 338 are formedsuch that a gap 342 is created on one side of the patient's toothbetween a portion of the area between the inner aligner 336 and theouter aligner 338. On the other side of the patient's tooth, the inneraligner 336 and the outer aligner 338 are formed such that the outeraligner 338 follows the form of the inner aligner 336 closely. Thus, inresponse to being snapped onto the patient's tooth, the inner aligner336, including the dimple 348, becomes deformed and is pushed outward bythe patient's tooth. However, since the outer aligner 338 is also formedto be the shape of the target tooth position 344 on one side of thepatient's tooth, the outer aligner 338 will prevent the gingival area ofthe inner aligner 336 from popping outwards as well as keep the inneraligner 336 in contact with the patient's tooth. Thus, the outer aligner338 applies a force against the dimple 348 (and hence the inner aligner336) at the gingival line 350 and also applies a force 352 against theinner aligner 336 at the incisal edge of the patient's tooth. Theaddition of the dimple 348 (or ridge, in other embodiments) near thegingival line enables an even greater force to be applied by the inneraligner 336 against the patient's tooth near the gingival line; theaddition of the dimple 348 enables the dual aligner assembly 340 to movethe root of the patient's tooth even more than that movement that iscreated and shown in FIG. 3C.

With reference to FIG. 4A, the current position 402 of the patient'stooth is shown, as well as the target tooth position 404 for thepatient's tooth, using a conventional aligner system having a singlealigner 406. The conventional aligner is shown, having been designed toform the shape of the target tooth position 404 and to move thepatient's tooth distally. Further, an attachment 408 is added to thetooth near the gingival line of the patient's tooth to help create moreforce via the contact between the single aligner 406 and the patient'stooth to move the root of the patient's tooth in the desired directionto reach the target tooth position 404.

With reference to FIG. 4B, the single aligner 406 of FIG. 4A is shownfrom a side perspective view as being snapped onto the patient's dentalarch (in this case, a portion of the single aligner 406 is shown snappedonto a patient's tooth). Since the patient's tooth is still in itsoriginal position, the single aligner 406 becomes deformed upon contactwith the patient's tooth. Such contact will push the single aligner 406open and create space 412 between the single aligner 406 and thepatient's tooth near the gingival line, so that the attachment 408 isnot fully engaged and not enough force is created to move the root ofthe patient's tooth to the desired position. Additionally, since theincisal edge is more rigid than the gingival portion of the singlealigner 406, at the incisal edge, in response to contact with thepatient's tooth, the single aligner 406 deforms less than thedeformations occurring at other less rigid portions of the singlealigner 406. The portion of the single aligner 406 near the gingivalline 426 tends to open outward to an extent dependent on its degree ofrigidity. Thus, since the force with which pressure is applied againstthe patient's tooth by the single aligner 406 is larger near the incisaledge 424 than at the gingival line 426, an unwanted torque is createdthat rotates the tooth in an unwanted direction.

With reference to FIG. 4C, a dual aligner assembly 420 is shown snappedonto the patient's teeth, in accordance with an embodiment. FIG. 4Cillustrates a portion of the outer aligner 418 and the inner aligner 416in relation to each other. Although not shown, the inner aligner 416 isformed to be in the shape of the target tooth position, while the outeraligner 418 is formed to be in the shape of the combination of thecurrent tooth position and the target tooth position. In response tobeing snapped onto the patient's tooth, the inner aligner 416 becomesdeformed and is pushed outward by the patient's tooth. However, sincethe outer aligner 418 is also formed to be in the shape of the targettooth position on the side of the attachment, the outer aligner 418 willprevent the inner aligner 416 at the gingival line 428 from poppingoutwards and keep the inner aligner 416 in contact and engaged with theattachment point 422 of the patient's tooth. This continued engagementcreates a bigger force with which the inner aligner 416 applies pressureto the patient's tooth in the distal direction.

Dual Aligner for Arch Expansion

Arch expansion is a frequently used technique to fix jaw crowdingmalocclusion. Arch expansion is done by moving posterior teeth (molarsand premolars) in the buccal direction. With the use of conventionalaligners, arch expansion may be difficult for several reasons.

Firstly, molars are bulky and are difficult to move by the conventionalaligner system.

Secondly, since the conventional aligner is made from the same plasticfilm with uniform thickness, the force that is applied to posteriorteeth is the same as the force applied to teeth other than the posteriorteeth. Due to the same force being applied to different areas of thedental arch, the process of moving groups of teeth using theconventional aligner system is difficult.

Thirdly, there are difficulties moving the middle teeth of a group ofteeth using the conventional aligner system. In general, conventionalaligners are formed based on a group of teeth that are positioned in thenext stage (i+1), so that there is no relative shape change for theteeth positioned in the middle of the group of teeth. With reference toFIG. 5A, an illustration describing the limitations of the conventionalaligner system and the benefits of the novel dual aligner assembly isprovided. An aligner is formed to have the shape of the patient's teethin the target tooth position. For example, the teeth T3, T4 and T5 aretargeted to move into the target tooth position 502, while all of theother teeth are targeted to remain in their current position. When thesingle aligner 504 is snapped onto the patient's dental arch, thealigner is deformed mostly between the moved and the stationary teeth,shown in FIG. 5A as being deformation area one 506 and deformation areatwo 508. Partly, this is because the portion of the single aligner 504surrounding the tooth T5 uses the portion of the aligner surrounding thetooth T6 as anchorage to provide support for pushing the tooth T5 towardthe target tooth position 502. However, there is not enough force tomove the middle tooth T4 to the target tooth position, since the toothT4 is between the two teeth, T3 and T5, which are already moving.Additionally, the neighboring teeth T2 and T6 to the moving teeth T3 andT5 may be receiving force from the deformation of the aligner occurringaround the aligner area near teeth T3 and T5, thereby creating unwantedmovement in the neighboring teeth T2 and T6.

According to FIG. 5A, the single aligner 504 presses against the lingualsurface of the teeth T3 and T5 to move the teeth T3 and T5 in an outwarddirection 510 and 512, but does not apply enough force to the middletargeted tooth T4 to cause the tooth T4 to also move in an outwarddirection 514. The teeth of the dental arch shown in FIG. 5A, other thanthe teeth T3, T4 and T5, are not targeted to move. It can be seen thatwhen the conventional aligner (single aligner 504) is snapped onto thepatient's dental arch, the aligner deformation mostly happens betweenthe moved and the stationary teeth, such as between the teeth T5 and T6at deformation area one 506 and between teeth T2 and T3 at deformationarea two 508. There may be enough force to move teeth that are near thestationary teeth, but there is not enough force provided by the singlealigner 504 against the patient's teeth to move the middle tooth T4 ofthe group of the targeted teeth.

FIG. 5B illustrates a dual aligner assembly 522 in operation, inaccordance with an embodiment. An inner aligner 520 is formed to havethe shape of the patient's teeth in the target tooth position 532. Forexample, the teeth T3, T4 and T5 are targeted to move to the targettooth position 532, while all of the other teeth are targeted to remainin their current position. An outer aligner 518 is formed to have theshape of the combination of the patient's teeth in their currentposition and the target tooth position 532. Dimples and/or ridges may beformed as part of the inner aligner 520 or attached thereto. Forexample, FIG. 5B shows dimple one 524, dimple two 526 and dimple three528 formed in the inner aligner 520 to fill a portion of the gap 530between the inner aligner 520 and the outer aligner 518 on the lingualside of the teeth. Upon snapping the dual aligner assembly 522 onto theteeth, the inner aligner 520 becomes deformed outward and the dimples524, 526 and 528 make contact with the outer aligner 518. Forces arethen created by which the inner aligner 520 presses against thepatient's teeth at the base of the dimple regions. The outer aligner 518is rigid enough such that each dimple positioned next to a differenttooth experiences about the same deformation, such that similar forcesagainst the teeth are created at the dimple regions (the dimple regionincludes the dimple base and point). The reaction forces 534 to thepressure applied by the inner aligner 520 against the patient's teethnear the dimple regions are then distributed such that the patient'sentire dental arch functions as an anchorage for the inner aligner 520to provide support for the movement of the target teeth, T3, T4 and T5.The outer aligner 518 provides support to the inner aligner 520, even atthe position of the middle tooth T4, such that the inner aligner 520 isable to provide enough force to the patient's middle tooth T4 to movethe middle tooth to the desired target tooth position 532. Instead ofbeing deformed outwards after being snapped onto the patient's teeth,the outer aligner 518 provides anchorage for the inner aligner 520,prevents the inner aligner 520 from deforming outwards, and keeps atleast portions of the inner aligner 520 in contact with the patient'steeth. Through such as system, the middle tooth T4 may also be moved toa target tooth position 532. As noted earlier, the outer aligner 518, inone embodiment, is made from a stronger and thicker material than theinner aligner 520. Additionally, since the outer aligner 518 is theenvelope of the current and the next position, there is minimumdeformation to the inner aligner 520 due to the tooth position change ofthe targeted teeth T3, T4 and T5. In contrast, in the conventionalaligner system with a single aligner, only the neighboring teeth wouldprovide anchorage support for the movement of the target teeth, T3, T4and T5.

Multiple Intermediate Aligners of the Dual Aligner Assembly

As described herein, in some embodiments, the dual aligner assemblyincludes an inner aligner, an outer aligner, and one or moreintermediate aligners for being positioned between the inner aligner andthe outer aligner. For example, in one embodiment, a dual alignerassembly includes a plurality of aligners. The plurality of alignersincludes a first aligner and a second aligner. The first alignerincludes a first material having a first shape corresponding to a firstset of target tooth positions, wherein the first aligner applies a firstorthodontic force against a set of target teeth of a plurality of teethof a dental arch of a patient, wherein the first orthodontic forcegenerates movement of the set of target teeth to the first set of targettooth positions. The second aligner includes a second material having asecond shape corresponding to a combination of current tooth positionsof the set of target teeth, the first set of target tooth positions, atleast a second set of target tooth positions, and a thickness of atleast the first aligner. According to some embodiments, there exists anintermediate aligner in between the first aligner and the secondaligner. The intermediate aligner is formed based on a second set oftarget tooth positions that is different from the first set of targettooth positions. The second aligner, in turn, accommodates not only thefirst set of target tooth positions considered by the first aligner, butone or more other sets of target tooth positions considered by the oneor more intermediate aligners. The second aligner also accommodates thethicknesses of the first aligner and any intermediate aligner.

According to an embodiment, the second aligner partially encloses atleast the first aligner (as well as any intermediate aligners) andprovides an anchor for at least a portion of at least the first aligner(and any intermediate aligners). Via the anchorage (the principal ofoperation of which is described herein), a combination of the firstaligner and the second aligner and any intermediate aligner positionedbetween the first aligner and the second aligner provide a secondorthodontic force that prevents the set of target teeth from moving tounwanted tooth positions during orthodontic treatment.

The term, “unwanted tooth positions”, includes tooth positions otherthan the following tooth positions: the current tooth positions of theset of target teeth; one or more tooth positions that represent movementof at least one tooth of the set of target teeth to any set of targettooth positions (including the first set of target tooth positions andat least a second set of target tooth positions); and any set of targettooth positions (including the first set of target tooth positions andat least a second set of target tooth positions).

Each of the inner aligners of the multiple aligners, in variousembodiments, may include inward and/or outward protrusions (e.g.,dimples, ridges, etc.), the operation of which are described herein.

Thus, in some embodiments, the dual aligner assembly includes three ormore aligners which are combined to provide more exact and desiredforces directed toward a predetermined tooth/teeth, in order to providea more efficient and accurate orthodontic process.

Manufacturing the Dual Aligner Assembly

In general, the steps of manufacturing the dual aligner assembly includethe following: 1) Create a mold of the jaw with the patient's teethpositioned in the next stage position. 2) Use a vacuum thermoformingprocess to create the inner aligner from the mold. 3) Create a combinedmodel of the patient's teeth, in the current stage and the nextposition. Then, inflate the model with a thickness of the inner alignerthickness. 4) Create a mold of a combined jaw model, using a vacuumthermoforming process to create the outer aligner from the mold. 5) Snapthe inner model into the outer aligner to create the “dual alignerassembly”.

The outer aligner is made from the combination of teeth from the currentposition of the patient's teeth (i) and the desired next stage position(i+1) of the patient's teeth. According to an embodiment, themanufacture of the outer aligner is different from the conventionalmanufacture of an aligner for the patient's teeth in the currentposition of the teeth as well as different from the conventionalmanufacture of a single aligner. Further, the manufacture of the outeraligner, according to embodiments, is different from the manufacture ofthe inner aligner of the dual aligner assembly.

A more detailed description of process for manufacturing the outeraligner is as follows.

To create the outer aligner, the first step is building a 3D solid modelto combine the teeth in two positions, as well as accommodating thethickness of the inner aligner. The process to create the 3D solid modelincludes the following:

1) For each of the patient's teeth, based on the tooth's next position,create a next position 3D tooth model.

2) Offset the next position 3D tooth model's surface by the inneraligner's thickness to create an offset 3D tooth model.

3) For each of the patient's teeth, based on the tooth's currentposition, create a current 3D tooth model.

4) For each of the patient's teeth, create a 0-N intermediateposition(s). Based on the intermediate position(s), create a 0-Nintermediate 3D model(s).

5) Through applying union Boolean operation on the offset 3D toothmodel, current 3D tooth model and 0-N intermediate 3D tooth model(s),create a combined tooth 3D model.

6) Through applying the union Boolean operation on all the teeth (on ajaw) combined 3D models and the jaw's gingival model, create a jawmold's 3D model, which is used for forming an outer aligner.

In the process described above, the current tooth position and the nexttooth position are used to create an outer aligner's mold model. Betweenthe current tooth position and the next tooth position, one moreintermediate tooth positions may be added to create intermediate 3Dtooth models. To create combined tooth 3D models, the union Booleanoperation is applied to an offset tooth model, to a current tooth modeland to an intermediate tooth model(s). By introducing the intermediatetooth model(s), the tooth movement is more guided from its currentposition to the next position and the aligner surface has smoothertransitions.

Referring now to FIG. 6, a dual aligner system 600 according to anembodiment of the present technology is illustrated. The description ofvarious embodiments shown in FIGS. 1A-5B may be incorporated into thestructure of the dual aligner system 600 shown in FIG. 6. As seen, thedual aligner system 600 includes an inner aligner 610 and an outeraligner 620. In one embodiment, the dual aligner system 600 is intendedto effect incremental repositioning of individual teeth in the jaw asdescribed generally above. The dual aligner system 600, in oneembodiment, includes a plurality of aligners (one or more inner alignersand an outer aligner), each having a polymeric shell having cavitiesshaped to receive and resiliently reposition teeth from one tootharrangement to a successive tooth arrangement. The polymeric shells, inone embodiment, will fit over all the teeth present in the upper orlower jaw. Often, only certain one(s) of the teeth will be repositionedwhile an aligner positioned exterior to an inner aligner provides a baseor anchor region for holding the inner aligner in place as it applies aresilient repositioning force against the set of target teeth to bepositioned at a set of target tooth positions.

It should be noted that any of the features disclosed herein may beuseful alone or in any suitable combination. While the foregoing isdirected to embodiments of the present invention, other and furtherembodiments of the invention may be implemented without departing fromthe scope of the invention, and the scope thereof is determined by theclaims that follow.

What we claim is:
 1. A multi-aligner assembly comprising: a plurality ofaligners, wherein said plurality of aligners comprises: a first alignercomprising a first material having a first rigidity, the first alignerfurther comprising tooth cavities having a first shape corresponding toa set of target tooth positions, wherein the first aligner applies afirst orthodontic force against a set of at least three adjacent targetteeth of a plurality of teeth of a dental arch of a patient, whereinsaid first orthodontic force generates movement of said set of at leastthree adjacent target teeth from a set of current tooth positions towardsaid set of target tooth positions through a desired treatment movementpathway; and a second aligner comprising a second material having asecond rigidity greater than said first rigidity, said second alignerconfigured to at least partially enclose the first aligner and envelopesaid set of at least three adjacent target teeth in said set of currenttooth positions, said set of target tooth positions, or a set of plannedpositions representing planned treatment movement to achieve said set oftarget tooth positions from said set of current tooth positions, whereinsaid second aligner is configured to anchor at least a portion of thefirst aligner, wherein via said anchoring, a combination of the firstaligner and said second aligner create one or more controlled forces tomove said set of at least three adjacent target teeth toward said set oftarget tooth positions through said desired treatment movement pathwayand the first aligner comprises a first force enlargement elementextending outwards and away from a cavity corresponding to an innertooth between outer teeth of said set of at least three adjacent targetteeth, such that when the multi-aligner assembly is snapped over theplurality of teeth and said second aligner is snapped over the firstaligner, said second aligner contacts and presses against the firstforce enlargement element and thereby is configured to increase saidfirst orthodontic force against the inner tooth of said set of at leastthree adjacent target teeth.
 2. The multi-aligner assembly of claim 1,wherein said desired treatment movement pathway excludes unwanted toothpositions other than: said set of current tooth positions of said set ofat least three adjacent target teeth; one or more tooth positions thatrepresent movement of at least one tooth of said set of at least threeadjacent target teeth to said set of target tooth positions; and saidset of target tooth positions.
 3. The multi-aligner assembly of claim 1,wherein the first aligner comprises a first thickness and said secondaligner comprises a second thickness greater than said first thickness.4. The multi-aligner assembly of claim 1, wherein the first alignercomprises an inner aligner and said second aligner comprises an outeraligner, wherein said outer aligner partially encloses said inneraligner.
 5. The multi-aligner assembly of claim 1, wherein themulti-aligner assembly comprises a gap between the first aligner andsaid second aligner, the first force enlargement element extending intosaid gap, and the first force enlargement element further comprising: acontact region between the first aligner and said second aligner,wherein the contact region provides an anchor point at said secondaligner and for the first aligner, the anchor point configured toimplement said anchor and to increase said first orthodontic forceagainst at least one tooth of said set of at least three adjacent targetteeth.
 6. The multi-aligner assembly of claim 5, wherein the first forceenlargement element comprises one or more of: a dimple, a ridge, and anoutward protrusion.
 7. The multi-aligner assembly of claim 1, furthercomprising: a second force enlargement element extending into a gapbetween the first aligner and said second aligner, and wherein a secondgap provides an area into which a movement of at least one tooth of saidset of at least three adjacent target teeth to at least one target toothposition of said set of target tooth positions is accomplished.
 8. Themulti-aligner assembly of claim 1, wherein the first force enlargementelement comprises one or more of: a dimple and a ridge.
 9. Amulti-aligner assembly comprising: a first aligner having a firstrigidity, the first aligner comprising tooth cavities having a firstshape corresponding to a set of target tooth positions, wherein thefirst aligner applies a first orthodontic force against a set of atleast three adjacent target teeth of a plurality of teeth of a dentalarch of a patient, wherein said first orthodontic force generatesmovement of said set of at least three adjacent target teeth from a setof current tooth positions toward said set of target tooth positionsthrough a desired treatment movement pathway; a second aligner having asecond rigidity greater than said first rigidity, said second alignerconfigured to at least partially enclose the first aligner and envelopesaid set of at least three adjacent target teeth in said set of currenttooth positions, said set of target tooth positions, or a set of plannedpositions representing planned treatment movement to achieve said set oftarget tooth positions from said set of current tooth positions, whereinsaid second aligner is configured to anchor at least a portion of thefirst aligner, wherein via said anchoring, a combination of the firstaligner and said second aligner create one or more controlled forces tomove said set of at least three adjacent target teeth toward said set oftarget tooth positions through the desired treatment movement pathwayand the first aligner comprises a first force enlargement elementextending outwards and away from a cavity corresponding to an innertooth between outer teeth of said set of at least three adjacent targetteeth, such that when the multi-aligner assembly is snapped over theplurality of teeth and said second aligner is snapped over the firstaligner, said second aligner contacts and presses against the firstforce enlargement element and thereby is configured to increase saidfirst orthodontic force against the inner tooth of said set of at leastthree adjacent target teeth.
 10. The multi-aligner assembly of claim 9,wherein the first aligner comprises a first thickness and said secondaligner comprises a second thickness greater than said first thickness.11. The multi-aligner assembly of claim 9, wherein the first alignercomprises an inner aligner and said second aligner comprises an outeraligner at least partially enclosing said inner aligner.
 12. Themulti-aligner assembly of claim 9, wherein the first force enlargementelement comprising one or more of: a dimple, a ridge, and an outwardprotrusion.
 13. A multi-aligner assembly comprising: a first alignerhaving a first rigidity, the first aligner further comprising toothcavities having a first shape corresponding to a set of target toothpositions, wherein the first aligner applies a first orthodontic forceagainst a set of at least three adjacent target teeth of a plurality ofteeth of a dental arch of a patient, wherein said first orthodonticforce generates movement of said set of at least three adjacent targetteeth from a set of current tooth positions toward said set of targettooth positions through a desired treatment movement pathway; and asecond aligner having a second rigidity greater than said firstrigidity, said second aligner configured to at least partially enclosethe first aligner and envelope said set of at least three adjacenttarget teeth in said set of current tooth positions, said set of atleast three adjacent target teeth in said set of target tooth positions,and said set of at least three adjacent target teeth in a set of plannedpositions representing planned treatment movement to achieve said set oftarget tooth positions from said set of current tooth positions, whereinsaid second aligner comprises means for anchoring at least a portion ofthe first aligner, wherein via said means for anchoring, a combinationof the first aligner and said second aligner create one or morecontrolled forces to move said set of at least three adjacent targetteeth toward said set of target tooth positions through said desiredtreatment movement pathway and the first aligner comprises a first forceenlargement element extending outwards and away from a cavitycorresponding to an inner tooth between outer teeth of said set of atleast three adjacent target teeth, such that when the multi-alignerassembly is snapped over the plurality of teeth and said second aligneris snapped over the first aligner, said second aligner contacts andpresses against the first force enlargement element and thereby isconfigured to increase said first orthodontic force against the innertooth of said set of at least three adjacent teeth.
 14. Themulti-aligner assembly of claim 1, wherein said one or more controlledforces apply pressure against a gingival line of said set of at leastthree adjacent target teeth.
 15. The multi-aligner assembly of claim 1,wherein said one or more controlled forces cause an inner surface of thefirst aligner to press against said set of at least three adjacenttarget teeth at one or more positions corresponding to the first forceenlargement element on the first aligner.
 16. The multi-aligner assemblyof claim 1, wherein said one or more controlled forces cause the firstaligner to push against said set of at least three adjacent target teethin a tangent direction relative to said set of at least three adjacenttarget teeth, thereby creating a rotation torque on said set of at leastthree adjacent target teeth.
 17. The multi-layer assembly of claim 1,wherein said one or more controlled forces provide tooth movementguidance to the first aligner to guide movement of said set of at leastthree adjacent target teeth along said desired treatment movementpathway.